Khemia is the sequel to Adastra and takes place a little over 2 years since the end of Adastra. As such, the human MC is still doing his mission on Earth and isn't present in the story (but we have only had a couple updates so far so that may change).
Amicus and others like Neferu are in the new story along with a number of new characters. Check it out at:
https://echoproject.itch.io/khemia